Volumetric apparatus such as a vacuum pump or the like,having an exact circular translation cycle



Oct. 21, 1969 P. VULLIEZ 3,473,728

VOLUHETRIC APPARATUS SUCH AS A. VACUUM PUMP OR THE' LIKE, HAVING ANEXACT CIRCULAR TRANSLATION CYCLE Filed on. 2, 1967 4- Sheets-Sheet 1FIG] .Oct. 21, 1969 P VULLIEZ 3,473,728

VOLUMETRIC APPARATUS SUCH AS A VACUUM 'PUMR OR THE" LIKE, HAVING ANEXACT CIRCULAR TRANSLATION CYCLE Filed Oct. 2, 1967 v4 Sheets-Sheet 2Arr/ 4 Sheets-Sheet 5 Awe/Wag 7 firrys.

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Oct. 21, 1969 VOLUMETRIC APPARATUS SUCH As A VACUUM PUMP on THE LIKE,HAVING AN EXACT CIRCULAR TRANSLATION CYCLE Filed 001"- 2, 1967 3 Z mm4???? n 7,? .w 1 L8 9 a M E g..:\\ 7 A .1. A 2 0 r l A- m 1 I Cl A A 3 2Oct. 21, p; U

VOLUMETRICAPPARAIUS SUCH AS ACUUM PUMPI 0R THEr LIKE, HAVING AN EXACTCIRCULAR TRANSLATION CYCLE v Filed Oct. 2, 1967 4 Sheets-Sheet 4 I 1/701, V0.4 4 /4-z a, N r'JM 3,473,728 VQLUMETRIC APPARATUS SUCH AS AVACUUM PUMP OR THE LIKE, HAVING AN EXACT CIR- CUlLAR TRANSLATION CYCLEPaul Vulliez, 13 Rue de la Brasserie, 27 Pont-Audemer, Eure, FranceFiled st. 2, 1967, Ser. No. 672,332 Claims priority, application France,Oct. 6, 1966, 78,983; Sept. 29, 1967, 122,797 Int. Ci. FtMc 17/02 U5.Cl. 23[i--146 Claims ABSTRACT OF THE DISCLOSURE A rotary machine such asa vacuum pump has at least one annular or spiral working member mountedfor circular movement on at least three spaced crankshafts so that thepoints of closest approach of the working member sweep the walls of theworking chamber but are at all times spaced from the walls of theWorking chamber by a small constant clearance. Fluidtight bellows sealbetween the machine body and the working member about the crankshafts,and the side walls are unlubricated. The combination of the smallclearance plus the lack of lubrication plus the bellows seal permits thetotal elimination of lubricant from the working chamber.

The present invention has for its object a volumetric cycle apparatussuch as a vacuum pump or the like, the fluid tightness of which bybellows is complete with respect to the ambient, and in which theworking parts move with respect to each other following an exact andgenerated circular translation cycle, without any friction contact orlubrication.

It is known that in order to isolate completely from the ambient bymeans of a metallic bellows or diaphragm a movin member having arotating cycle, mounted inside a fixed casing, a very effective means isto create this rotating cycle by following an exact and generatedcircular translation, the fluid'tight sealing member being thenassociated on the one hand with the moving member and on the other handwith the fixed casing. By means of the exact and generated circulartranslation movement, the moving member describes a rotating cyclehaving an absolutely constant orientation, while the fluid-tight memberwhich is associated therewith is thus protected against any functionalor accidental torsion force.

In an apparatus of this kind, in addition to the protection of thefluid-tight sealing members against the effects of torsion, it isabsolutely essential to maintain connited States Patent 0 stant the verysmall radial or lateral clearance between i the working members of thepump, so as to prevent any accidental contact and to obtain the bestpumping performance. To this end, and taking into account theirgeometrical shapes and the reactions resulting from the work of pumping,these working parts must therefore move with respect to each other withthe minimum radial and lateral play.

The solution which has been advantageously chosen in order to obtainthis result is an exact and generated circular translation of the movingparts, effected by three synchronized eccentrics, the synchronizationbeing obtained, either by the moving part itself or by a transfer membercoupled to the moving part; in both cases, one of the eccentric shaftsis a driving shaft.

With this construction comprising three synchronized eccentrics, themoving parts are maintained laterally in clearly defined planes, andradially the circular translation motion can be obtained with themaximum mechanical precision.

The rotary machine of the present invention comprises 3,473,728 PatentedOct. 21, 1969 "Ice a fixed body having an inlet and an outlet for aworking fluid and a passageway for the working fluid extending betweensaid inlet and outlet and disposed within said body, movable means forelfecting displacement of the working fluid from said inlet to saidoutlet, a mechanism by which said movable means is connected with andsupported relative to said body, said mechanism comprising at leastthree crankshafts of equal eccentricity and synchronously coupled to oneanother for controlling circular-translatory movement of said movablemeans relative to said body during operation of the machine, means fordriving said movable means to effect said movement, said passagewayhaving walls that are shaped to match the configuration of the envelopeof the space swept by said movable means during movement thereof, saidmovable means and the most adjacent walls of said passageway beingspaced by a small constant clearance in any position of said movablemeans, and fluid-tight bellows means having ends fixed respectively tosaid movable means and to said body for isolating said passageway fromthe atmosphere, and permitting its operation Without any frictioncontact between the parts that are exposed to the interior of thepassageway and therefore without any lubrication.

In one form of construction with a spiral ring, there may be employedtwo identical spiral rings, each with a side plate, both moving and setat from each other, one moving inside the other so as to constitute thewhole of the active portion of the pump. This solution makes it possibleto obtain, by construction, a perfect balance, while a double pumpingvolume is generated for the same lateral displacement of the fluid-tightbellows.

The coupling means between the moving member and the fixed body orbetween the two moving members, comprise, for each moving member, atleast three cranks having the same orientation and equal eccentricityand synchronized by the moving member itself, at least one of the saidcranks being a driving crank.

When the moving member in the form of an open ring is of suitabledimensions, it may be made hollow and the driving cranks are thenmounted traversing inside the ring, and bellows means or fluid-tightmembranes in the form of sleeves of any material such as metal orplastic, are arranged in the hollow ring and surround the cranks whilehaving one of their extremities coupled to the fixed body and the otherextremity to the ring. This construction is balanced from the point ofview of axial reaction resulting from the pressure.

In the other cases in which thin moving parts are employed, that is tosay having reduced thickness, the mounting of these moving parts iseffected on an end-plate, which receives, following a lateral mounting,the action of the .coupling means with the body for giving it an exactcircular movement of translation. 7 Y

This construction, obtainable with three bellows, can also be obtainedwith a single central bellows, inside which is located the rigidcoupling member which fixes the moving member to the movement transfermember (see FIG. 9).

It will of coure be understood that these various forms of constructionmay be utilized in combination with each other.

According to the invention, the shape of the moving parts and of theircurved casings is designed so as to prevent the back flow of thedelivery fluid towards the suction, and also the complete emptying ofthe pumping chamber at the end of the delivery period.

While maintaining the above advantages, the invention also relates to aconstruction of a multi-stage pump for the application of vacuum or thecompression 0 gaseous fluids.

In this connection, note should be made of the remarkable propertiesobtained with the construction having two identical spiral rings,whether they are both moving or whether one is fixed and the othermoving. Starting from the center of the spiral rings and limiting theirangular development to 360, it is found that at the end of the suctionstage there is imprisoned a volume V which is wholly and graduallyexpelled after a single cycle of circular translation, the separationbetween the exhaust and the suction being constantly maintained byprogressive and continuous juxtaposition at a distance equal to thesmall constant clearance of the spiral moving members.

Again starting from the center of the spiral rings and with an angulardevelopment of the volutes equal to twice 360, the volume V1 imprisonedat the suction is brought at the end of a cycle of circular translationand in a progressive manner, to the volume V having a value less thanV1. It is then transferred during the course of a second cycle ofcircular translation to the first portion of 360 of angular developmentof the spiral ring and is completely expelled. The operation of a spiralring of twice 360 of angular development becomes that of a pump with twostages. The continuous separation between the suction and delivery isconstantly and doubly ensured by two continuous contacts on each spiral.

In this way it is possible to multiply the number of stages of the pump,each stage ensuring an independent progressive compression beforereaching the volume V of suction of the last stage.

The objects, characteristic features and advantages of the inventionwill further be brought out in the description which follows below offorms of construction selected by way of examples, reference being madeto the accompanying drawings, in which:

FIG. 1 is a diagrammatic view in a direction parallel to the axis of asingle-stage pump having a thick moving member traversed by the threedriving cranks and three fluid-tight bellows, and with a static anddynamic balancing mass.

FIG. 2 is a view of this apparatus in cross-section, taken along thebroken line II-II of FIG. 1.

FIG. 3 is a diagrammatic view showing the operation of spiral rings in asingle stage;

FIGS. 4 and 5 are diagrammatic views showing the operation of spiralrings having two stages.

FIG. 6 is a diagrammatic view in a'direction parallel to the axis of atwo-stage pump with two moving spiral rings and a shelf-balancedassembly.

FIG. 7 is a view of this apparatus in cross-section taken along thebroken line VIIVII of FIG. 6.

FIG. 8 is a diagrammatic view perpendicular to the axis of a two-stagepump with one fixed spiral ring and the other ring moving, the assemblybeing effected laterally with a single central bellows and balancing byadditional weight.

FIG. 9 is a view of this apparatus in cross-section taken along theaxial line 1XD( of FIG. 8.

Reference will first be made to FIGS. 1 and 2 which relate, by way ofnon-limitative example, to an application of the invention to avolumetric vacuum pump of absolutely fluid-tight construction and havingan internal operation with low friction and without lubrication, all thecoupling members comprising bearings being strictly isolated from thepumping chamber by metallic bellows means.

As shown in FIGS. 1 and 2, the pump comprises a fixed body 10 made up ofa cylindrical outer wall 11, a cylindrical inner wall 12 concentric withthat preceding, and two lateral closure walls 13 and 14. The axis A ofthe cylindrical walls 11 and 12 of the body 10 is represented b a pointin FIG. 1 and by a chain-dotted The pump also comprises a moving member16 engaged in the cavity 15, which is constituted by a circular ringopen at 17 and made hollow with a section along a radial planeadvantageously in the general shape or a caisson so as to house freelythe cranks 18 which, in this non-limitative assembly, constitute thecoupling means with the fixed body in order to generate an exactcircular translation travel.

The extremity of the ring on the suction side is out along a radialplane extended by a semi-cylindrical part 19 which ensures contact withthe fixed part 12 so as to prevent any intercommunication between thedelivery and the suction when the moving member is in contact with theouter wall 11, according to the instantaneous position of FIG. 1. On thedelivery side, the moving member is terminated by a cylindrical portion,the envelope curve of which is constituted by the partition 30. Thespace 17 is in communication with the suction 27.

The coupling means between the moving member 16 and the body 10 comprisethree eccentric means arranged at 120 and each consisting of a crank 18.This latter has a portion 20 mounted for rotation on the body 10 andheld by the barrel 21 by means of bearings and abutments. The portion18, eccentric by the amount E is also maintained by a guiding barrel 22rigidly fixed to the moving member 16. By means of this mounting, theelfects of bending on the crank-shafts 18 are reduced to the maximumextent. Locking systems for the thrustbearings 36 ensure thedistribution of the working play between the lateral faces of the movingmember and the body. The amount of eccentricity E shown in FIG. Idefines the exact circular radius of translation of the moving member16.

In this construction, the drive is effected from the central shaft 26,on which is keyed the balancing weight 25. A coupling member 24 ensuresthe rigid fixing of the crank-shafts 18 with the central shaft 26 bymeans of eccetric arms. It should be noted that this fixing isnecessitated by the presence of the balancing weight 25, thecrank-shafts 18 being already synchronized with each other by the movingmember 16.

Fluid-tight bellows 23, in the form of sleeves, are also housed insidethe ring 16 and surround the cranks 18. Each bellows 23 is rigidly fixedat one extremity 28 to the barrel 21 fixed to the body 10, and by theother extremity 29 to the barrel 22 fixed to the moving member 16 Eachbellows 23 is free from any torsion force by means of the mounting ofthe three cranks 18 which generate an exact circular translationmovement of the moving member, and has only a slight undulating movementwhich only produces negligible fatigue. The bellows may be made of anysuitable material, metallic, plastic or the like, and provide completelyfluid-tight sealing.

It will be appreciated that the exact circular translation movementgenerated by the member 16 is efiected by a plurality (a minimum ofthree and non-aligned) of cranks 18 having an eccentricity E andsynchronized line in FIG. 2. The walls 11 and 12 form between them bythe member 16 itself. Without the static and dynamic balancing weight25, the fixing member 24 could be dispensed with, the pump being thenactuated by the single drive of one of the shafts 18.

As in the case of all the remaining figures, the direction of runningcorresponds to a rotation of the eccentrics in the direction of thearrows 30.

The wall 11 comprises an orifice 27 for admission of fluid, while theface 14 may comprise two delivery valves 31 and 32 communicatingrespectively with the radially inner and radially outer parts of thecavity.

Considering FIG. 1, it can be seen that for a working cycle, the volumegenerated by the action of the internal and external cylindrical wallsof the ring 16 with their envelope curves is theoretically equal to thedifference in volume between the cavity 15 and the ring 16.

In the instantaneous position of the moving member such as shown in FIG.1, it is clearly seen that on the delivery side, the contact is neverinterrupted between the moving member 16 and its envelope curves of thecavity 15. In this same instantaneous position, the fluid compressedoutside the moving member 16 partly escapes through the valve 32, thenon-expelled volume then passing in the chamber on the inner face sideof the moving member 16 and is then totally expelled through the valve31, the separation between the suction and delivery being constantlymaintained, in particularly by means of the part 19.

It will be noted that the parasitic volume located in the interior ofthe ring and the exterior of the metal bellows can readily be put intocommunication with the suction alone; it is then subjected to thepressure of the chamber to be pumped.

Reference will now be made to diagrammatic FIGS. 3, 4 and 5 which showthe course of the pumping cycles with a moving member in the form of aspiral ring, moving in exact circular translation movement in theinterior of a fixed portion constituted by an envelope curve having anidentical spiral outline.

According to FIG. 3, there can be seen a moving member 16, the angulardevelopment of which is 360 and the envelope curve 12 of which is fixedto the body and has a spiral outline identical with the starting pointlocated at B.

The outline of the spiral moving member is advantageously formed bysemi-cylindrical portions having their centers at M1 and M2, the centersof the fixed spiral being at M3 and M4. The circular translationmovement of the moving member is effected by three eccentrics rotatingin the direction of the arrows 30 with a radius of eccentricity equal toE.

The suction at 27 is extended between the exterior of the moving ring 16and the wall of the body 10 up to the point B at which the activepumping starts. The delivery is effected at the center through theorifice 31 (not shown in FIGS. 4 and 5 for the sake of clearness of thedrawings).

According to the instantaneous position of the moving member 16 in FIG.3, it is seen that the suction is taking place while the delivery intothe central portion of the volume imprisoned during the preceding cycleis also in course.

Referring to FIG. 4, it can be seen that for the portion of spiral ringof 360 in angular development, as shown in FIG. 3, the suction iscompleted when the contacts B1 and B2 are established, the two volumes Vimprisoned during the previous cycle then being completely expelled fora ring of this kind, a single cycle of circular translation makes itpossible to isolate two volumes V, which are then joined together andprogressively compressed, so as to be completely expelled through theorifice 31. The separation between the two suction zones 27 and thedelivery 31 is constantly ensured by the continuous displacement of thecontacts B1 and B2 (see FIG. 5) which return to the position of FIG. 4when the end of delivery contact B3 is established.

The operation of a spiral ring with an angular development of 360corresponds to that of a vacuum pump having a single stage.

Consider again the assembly of FIG. 4, in which the moving member 16 hasan angular development of twice 360. In the instantaneous position ofthis figure, it is seen that by the contacts B4 and B5 two volumes V1have just been isolated at the end of the suction period. At the end ofa first cycle of circular translation, the two volumes V1 areprogressively compressed to a value V less than V1. This progressivecompression, of which an intermediate position is shown in FIG. 5, ispossible by the continuous displacement of the separation contacts (towithin the clearance) bringing B4 to B1 and B5 to B2. At the end of asecond cycle of circular translation, the two volumes V are firstre-united and then progressively compressed and expelled through theorifice 31, as previously explained.

In this connection, FIG. 5 shows an intermediate position in which, withrespect to FIG. 4, the moving member 16 has moved through a portion of acycle corresponding to a rotation in the direction 30 through an angle aof the driving eccentrics. In this position, the next following suctionat 27 is in course, the two volumes V1 of FIG. 4 having become V2, andthe two volumes V of the same FIG. 4 being joined together at V3,following a position of the moving member 16 preceding the totaldelivery. It can be seen that the barriers B1, B2, B4 and B5, whileoccupying new positions, still effect the separation between the volumesof each of the stages and also between the volumes V2 and the suction.

It is thus found that the operation of a spiral ring of twice 360 inangular development is the same as that of a vacuum pump with twostages. Each stage effects its own compression in a progressive mannerby the fact of the continuous separation (to within the workingclearance) between the suction and the first compressed volume on theone hand and, on the other hand, between this first volume and thesecond volume expelled following the cycle of FIG. 3.

The full advantage of this construction will be understood, whichpermits, especially in the application to vacuum pumps, a multiplicationof the number of stages with a single apparatus, in which the workingparts of the pump are either one fixed and the other moving or bothmoving and set at 180 from each other.

FIGS. 6 and 7 give a non-limitative example of a pump in which theworking portion is constituted by two identical moving members movingone inside the other so as to form a two-stage assembly which isstatically and dynamically self-balanced.

The two identical moving members 16a and 16b having an angulardevelopment of twice 360, are each provided with a lateral end-plate at35a and 35b respectively. The moving member 16b is coupled to itstransfer member 33b by means of three rigid couplings 22b passing intothe interior of the bellows 23. These bellows 23 are fast with the fixedbody 10 at 28 and with the end-plate 35b at 29. The transfer member 33bis driven in exact circular translation movement by the rotation of thethree cranks 18b associated with three shafts 20 centered in the body 10by hearing means located at from each other, as shown in FIG. 6.

The coupling means between the moving member 16a and its transfer member33a, not shown on the drawings, are mounted in exactly the same mannerand symmetrically with those of the moving member 16b. The transfermember 33a of the moving member 16a is driven in an exact circulartranslation movement by the action of the three eccentrics 18a alsobelonging to the shafts 20, these eccentrics 18a being each fixed atwith respect to each of the eccentrics 18b.

The adjustment of the lateral clearance between a moving member and theend-plate of the other moving member is effected by abutment means 36.

The two working portions 16a and 16b being moving, the delivery 31 iscoupled to the body 10 by a bellows means or diaphragm 34.

The construction with the working part of the pump formed by two spiralmoving rings, in addition to the facility of static and dynamicbalancing, enables the amplitude of displacement of the two spiralrings, one with respect to the other, to be doubled for the same lateraldisplacement of the bellows 23, this being in comparison with thesolution having one fixed spiral ring while the other ring is moving.

The construction can of course be envisaged with the moving member 16asecured to the fixed body 10, the moving member 16b being simply drivenby three cranks, following a construction comparable with that of FIG.2. This construction necessitates the addition of static and dynamicbalancing weights.

FIGS. 8 and 9 relate to a pump with a moving member 16 having a spiralring of twice 360 in angular develop ment, moving in the interior of afixed portion constituted by an identical spiral ring 12 belonging tothe body 10.

The spiral moving ring 16 comprises an end-plate 35 rigidly fixed to thetransfer member 33 by the rigid coupling member 22 located inside thesingle bellows 23.

The transfer member 33 is given an exact circular translation movementby the action of the three cranks 18 belonging to the three shafts 2i)centered on the body by bearings arranged peripherally at 120 from eachother. Abutment means 36 permit the adjustment of the lateral clearancebetween the moving member 16 and the corresponding working parts of thebody 10.

The suction is effected along 27, and the delivery is located at 31 witha valve.

The dynamic and static balancing is eflected by means of an additionalweight 25 put into circular translation movement by the three eccentrics37 keyed on the shaft 20 with 180 displacement with respect to thecranks 18.

This construction is preferably employed in the case of pumps of smalloutput.

As in the case of FIGS. 6 and 7, the exact circular translation movementis generated by the rotation of one of the shafts 20.

What I claim is:

1. A rotary machine comprising a fixed body having an inlet and anoutlet for a working fluid and a passageway for the working fluidextending between said inlet and outlet and disposed within said body,movable means for effecting displacement of the working fluid from saidinlet to said outlet, a mechanism by which said movable means isconnected with and supported relative to said body, said mechanismcomprising at least three crankshafts of equal eccentricity andsynchronously coupled to one another for controllingcircular-translatory movement of said movable means relative to saidbody during operation of the machine, means for driving said movablemeans to eflect said movement, said passageway having walls that areshaped to match the configuration of the envelope of the space swept bysaid movable means during movement thereof, said movable means and themost adjacent walls of said passageway being spaced by a small constantclearance in any position of said movable means, and fluidtight bellowsmeans having ends fixed respectively to said movable means and to saidbody for isolating said passageway from the atmosphere.

2. A rotary machine as claimed in claim 1, said movable means being ofsplit-ring shape, said passageway walls including cylindrical walls anda partition wall extending through the split of the ring, said inlet andsaid outlet being disposed on opposite sides of said partition wall.

3. A rotary machine as claimed in claim 1, said movable means being inthe form of a hollow box, said crank- 8 shaft extending at least in partwithin said box, said bellows means comprising a plurality ofsleeve-shaped bellows each of which surrounds a crankshaft.

4. A rotary machine as claimed in claim 1, said movable means comprisinga first disc having a first spiralshaped projection on one side thereof,said body comprising a second disc opposite to said first disc andhaving a second spiral-shaped projection on one side thereof interleavedwith said first projection, said first and second projections having thesame angular extent, and connecting stub means rigid with one of saiddiscs and extending on the side thereof which is opposite to theprojection thereon, said bellows means surrounding said connecting stubmeans.

5. A rotary machine as claimed in claim 4, in the form of a single-stagevacuum pump, said angular extent being 360.

6. A rotary machine as claimed in claim 4, in the form of a plural-stagevacuum pump, said angular extent being at least twice 360.

7. A rotary machine as claimed in claim 1, said outlet being soconstructed and arranged as to be alternately exposed by and completelyswept by said movable means whereby said passageway has no residualvolume adjacent said outlet.

8. A rotary machine as claimed in claim 1, said movable means comprisinga first member and a second member, said first and second members beingof spiral shape. said mechanism moving said first and second membersrelative to each other with equal eccentricities and equal rotationalspeeds but out of phase with each other.

9. A rotary machine as claimed in claim 8, said crankshafts being doublecrankshafts having eccentric portions one to drive said first member andthe other to drive said second member.

10. A rotary machine as claimed in claim 1, said movable means being inthe form of a spiral that coacts with a spiral rigid with said body.

References Cited UNITED STATES PATENTS 1,041,721 10/1912 Ball 91--561,376,291 4/1921 Rolkerr 230-l46 3,011,694 12/1961 Audemar 23Gl463,161,141 12/1964 Refson 103l32 3,194,167 7/1965 Wilson l03132 FOREIGNPATENTS 486,192 5/1938 Great Britain.

DONLEY J. STOCKING, Primary Examiner W. J. GOODLIN, Assistant Examiner

